Unfortunately optimistic. They don't really control the important part of the timetables. Assuming the tariffs lead to the hoped for results, the progression is something like;
[Tariffs](You Are Here) => [Business loses customers or profits due to higher costs] => [Business starts to build local supply chains to avoid tariffs and reduce costs] => [Local supply chains employ Americans and drive wage competition] => [More employed Americans, all employed Americans better off]
Unfortunately, that middle ground is entirely in the hands of business, and entirely dependent on their actions to get to the better off part. For some, it may only be a matter of months to move local, others may take years, or even longer. Its really circumstantial, and that middle ground will hurt the entire way.
Worth it in the long run though. Shit was gonna get worse either way, I'd rather it get worse to set the stage for a better period, than to get worse to pad NGO pockets.